Siding and roofing coverings made of synthetic materials for facing exterior building walls and roofs are known. They can have the appearance of wooden clapboards, cedar shakes, masonry such as stones and bricks, and the like. The coverings include elongated panels which are individually nailed or screwed to building walls or roofs, i.e. to support surfaces. These panels are commonly nailed to the support surface in horizontal courses, beginning with the lowermost course. Typically, an upper marginal edge region of the panels is provided with a plurality of longitudinally-spaced outwardly and downwardly directed interlocked hook-shaped fingers protruding from a front surface and a lower marginal edge region of the panels is provided with a bottom upturned hook-shaped rail formed on the underside of the panel, as disclosed in U.S. patent application 2008/0098683. The interlocked fingers of an underlying panel are engaged with the bottom rail of an overlying panel.
However, due to the size of the panels, the installer may have difficulty to engage all the interlocked fingers with the rail. Furthermore, the engagement of the fingers and the rail does not secure the overlying panel to the underlying panel and it can be difficult for the installer to hold and maintain a panel and simultaneously secure it to the support surface.